1. Field of the Invention
The present invention relates to a handcart for use in conveyance which enables the direction of progress of a self-propelled car to be readily changed.
2. Description of the Related Art
Electric motor driven self-propelled cars have been used in the operations in a greenhouse (a hothouse), which are required to grow, for example, vegetables. Such self-propelled cars are capable of moving back and forth between ridges in the greenhouse, and are used to sprinkle water or spray chemicals over the plants.
It is general that the above-described type self-propelled car can automatically move back and forth along a longitudinal region between adjacent ridges but that it must be manually moved in the lateral direction in a head region to a position where it faces another adjacent longitudinal region.
Japanese Utility Model Unexamined Publication No. 58-189783 discloses a technique for automatically moving this self-propelled car in the lateral direction in the head region to a position where it faces another adjacent longitudinal region. In this technique, an electric motor driven self-propelled cart capable of moving in the lateral direction with the self-propelled car placed thereon is provided.
However, in the conventional technique of the above-described type, both the self-propelled car and the cart are respectively provided with a driving device. One of the driving devices is not used at all while the self-propelled car or the cart is being moved in its associated direction. Furthermore, switch-over operation between the two driving devices requires a complicated structure.
Furthermore, a special consideration has to be made to safely absorb the running force by inertia without applying overloads on the individual components when the self-propelled car is automatically stopped at a predetermined position on the cart. Hence, the overall size and the weight of the apparatus are increased, and the production cost is increased. Installation of the apparatus is a troublesome work, and a failure readily occurs.